Etched electrode



Aug. 31, J. 5 WILUAMS 2,091,576

ETCHED ELECTRODE Filed Feb. 15, 1936 2 Sheets-Sheet l INVENTO ATTORNEY Aug. 31, 1937. J. 5. wlLLlAM 2,091,575

ETCHED ELECTRODE Filed Feb. 15, 1936 2 Sheets-Sheet 2 irmum TOR a INVENTOR ATTORNEY Patented, Aug. 31, 1937 UNITED STATES PATENT OFFICE ETCKED ELECTRODE Joseph, Senn Williams, Indianapolis, Ind., as

signor to P. R. Mallory & 00., Inc., lndianapolis, Ind., a corporation of Delaware Application February 15, 1936, Serial No; 84,012

12 Claims.

This invention relates to etched electrodes for electrolytic condensers and the like.

An object of the invention is to provide etched electrode of improved type.

5 Other objects of the invention will be -.app a rent from the following description and accompanying drawings taken in connection with the appended claims.

The invention comprises the features of cone- 2m nection with. the accompanying drawings, in

- which:

Figure 1 is a face view of a section of an etched electrode arranged according'to one form of the invention;

Figure 2 indicates a slightly different construction; e

Figure 3 is a face .view of a narrower electrode;

Figure 4 shows a modified form of electrode;

Figure 5 shows a further modification;

Figure 6 represents a still further modification;

Figure Us a section of a condenser; and

Figure 8'illustrates an apparatus for etching the electrodes according to the present inven- 85 tion.

tion is described herein, it is contemplated that considerable variation may be made in the meth- 0d of procedure and the construction of parts without departing from the spirit of the invention. In the following description and in the claims, parts will be identified by specific names for convenience, but they are intended to be as generic in their application to similar parts as 6 the art will permit. l Electrodes for electrolytic devices are some times etched to increase thelr'effective surface area. In the case of electrolytic condenser electrodes this materially increases the capacity obtainable per unit'area of electrode surface.

In dry electrolytic condensers the electrodes are usually made of thin aluminum foil and are provided with'terminals either secured to the foil or comprising tabs forming an integral part ot the electrode foil. It has been found that the the following detailed description takenin con- While a preferred embodiment of the inven etching" operation, while materially increasing the capacity, results in a certain amount of weakening of the electrode foil. This weakening, resulting from the reduction in cross section and from increased embrittlement of the foil, rendersthe tab connections less secure and more liable to failure.

According to one aspect of the present invention selected areas of the electrode are etched to obtain increased eflective surface while other areas .are leift unetched to provide greater strength. I Y

Referring to the drawings, Figure 1 shows a lengthof etched foil having etched sections it adapted to provide areas of enhanced capacity in the completed condenser and having unetched strips ll extending across the foil at intervals. Strips it may be completely unetchecl, in which case their surfaces may appear the same as that of the. original unetched foil, or the strips it may also be etched, but in a reduced degree, so that they present higher strength than the portions iii. It is preferred that both faces of the foil be treated similarly so that the difl'erence in regions i6 and it will also be present on the opposite face.

, dry electrolytic condenser it may be out into suit- In using the etched foil for an electrode in a able lengths so as to include one or more of the sections it for the terminal connections. The terminals may be applied to sections H either before or after cutting the foil into electrode lengths. They may comprise metal strips or wires attached to'the foil, for instance in the manner set forth in H. F. Fruth Patent No. 2,020,408 on a Condenser foil terminai, or they may comprise tabs formed directly from the elec= trode metal itself. These tabs may be formed in one of the ways commonly used in the prior art or they may m formed as indicated in the various figures.

In Figure l, for example, the tab it is formed. by cutting sill-shaped slit in one of the sections ii and folding out the tab so as to leave an aperture having its edges It bounded by the foil. This novel tab, as well as those shown in, Figures 2, 5 and 6, is coveredin sec-pending application of Omar. L. F luharty, Serial No. 64,052, illed February 15, 1936.

v Figure 2 shows an etched foil 20 having unetched sections 2i and indicates how. an improved tab 12 can be formed by cutting or punching at" so that the entire tab is surrounded by unetched foil.

Figure 3 shows a length offoil having etched v 33 and refolding two or three more times as at 0 into the' etchingbath or they may be treated or.

with a layer of paper or other sheet material M to give a tab of suitable width.

Figure 4 shows a foil having an etched Surface it with unetched sections li along one edge at intervals. It is also indicated in this figure how a tab :32 can be formed by cutting along twoedges 5d of the section ii and folding diagonally at 33.

Figure 5 shows a foil having etched sections 58 and an unetched section iii diagonally across the electrode. A tab may be provided by making a U-shaped cut at 53 and folding the tab out as indicated by 52. 1

In Figure 6 an unetched section El is left in the etched surface $9 of such shape as to suitably form a tab 62 when a cut is made around the edges.

Figure 7 shows a dry electrolytic condenser comprising a container 63 in which a condenser section 65 is enclosed, the section 65 comprising a pair of etched foils having unetched or partially etched sections for terminals as shown in the previous figures. from each other and include between them an electrolyte adapted to maintain a current-block ing film thereon. At least one of the electrodes may preferably be film-formed before'assembly. Condenser section 65 is embedded in pitch 6 5. A cover 68 is provided on container 63 and a pair of terminals 6th and 57a project therethrough. Tabs 66 and 61' are connected to the two electrodes, respectively, in one of the ways indicated in the preceding figures and are secured, respectively, to terminals 66a and did.

In order to prevent the attack of the foil sections selected for tabs during etching of the rest of the. foil the sections may be kept from dipping immunized to prevent or impede the attack of the etching medium. This may be done, for example, by coating the sections with a layer of parafiin or other immunizing substance, covering adapted to retard etching action or by forming an integral film on the surface in a manner similar to that-used in anodizing or in film-forming the electrodes of electrolytic condensers. It has also been found that etching can be inhibited by drying the foil section in air between the cleaning and etching steps.

Figure 8 shows a continuous process galvanic etching apparatus similar to that set forth in J. M. Booe'Patent No. 2,052,962 for Process of etching but-having added means for immunizing predetermined sections of the foil to the etching medium. Asindicated in this figure unetched;

foil H is unwound from roll 19 and passes through a cleaning solution 72, such as caustic, in tank 73,

the foil being guided by roller id. On emerging from thecleaning solution the foil passes over v roller i5 and into a tankii of wash water it felt rollers 82 and 83 saturated with a suitable material for immunizing the foil. Roller 82 is supported on a lever arm 84 pivotedat 85 and The foil electrodes are spaced I acetate provided with a small roller 86 adapted to ride 1 on a cam M.

Cam Bl is driven by a bevel gear 88 whichis, in turn, driven by the driving means 89 which also draws the foil through the apparatus. An adjustable speed regulator 90 is provided between drive means 89 and bevel gears 88 so that the speed of the cam iii can be controlled to give any desired spacing between the unetched sections. The re%- nected to the metal hubs of rollers 82 and 83 the foil being connected to the positive terminal.

In operation the cam 87 presses roller 82 down ontothe foil ii at predetermined intervals, the foil being displaced sufficiently to make contact also with roller 83. The sections of foil contacted by rollers 82 and 83 will become filmed with a thin layer which will prevent any substantial etching of these sections. I

After having the predetermined sections immunized and passing through the second tank of wash water the foil is led up over roller andthen passes through etching tank 97 having an etchingbath 96 therein. The foil passes between a pair of screens, one screen 99 being carried by three rollers M18, l0! and H02 and the other being mounted on the periphery of large roller 98. The etching bath, in co-operation with the screens causes an etching of the untreated areas of the foil surface but the immunized sections remain unattacked, or substantially so.

Upon leaving the etching tank the foil passes, over roller 0% and through wash water Q06 in tank W5 and wash water we in tank H19, guided by rollers we, E81; M0 and iii. The foil is then wound onto roll M2, the mandrel therefor being 82 and 33 they can be heated and soaked in melted paraifin for coating onto the foil. In this case generator 9! will not be required. Etching can. also be inhibited by covering sections of the foil with strips of paper which will separate the foil and the wire screens.

While the present invention, as to its objects and advantages has been described herein as. carried out in specific embodiments thereof, it is not desired to be limited thereby but it is intended to cover the invention broadly within the spirit and scope of the appended claims.

What is claimed is: g 1. An electrode unit for electrolytic device comprising a metal member having a section of its'surface etched and a section of its surface unetched, and a terminal for said electrode on the unetched portion thereof. I

2. An electrode unit for electrolytic devices comprising a metal member having a section of its surface fully-etched and a section of its surface much less than fully etched whereby it is stronger than said fully etched section, and an terminal for said electrode connected to said section which is less than fully etched. 3. An electrode for electrolytic devices comprising a sheet of foil of film-forming metal, said foil having a first section of its surfaceetched and a second section of its surface Substantially unetched, and a terminal for said electrode seface much less etched than the surface of said first section, and a terminal for said electrode 10 connected to said second section.

5. An electrode for electrolytic condensers comprising a strip of film-forming metal foil, a first section of said strip having an etched surface and a second section of said strip having a sin"- 15 face much less etched than the surface of said first section, and a terminal tabintegral with said second section.

6. An electrode for electrolytic condensers comprising a strip of film-forming metal foil, a first 20 section of said strip having an etched surface and a second section of said strip having a surface much less fully etched than the surface of said first section, and a terminal tab integral with said second section and comprising a por- 25 tion of the foil of said section.

7. An electrode for electrolytic condensers comprising a. strip of metal foil, a section of said strip of foil being etched, a section of said strip of foil being unetched and a terminal for said 30 electrode secured to said unetched section.

8. An electrode for electrolytic condensers comprising a strip of metal foil. section of said strip of foil being etched, a section of said strip of foil being unetched, and a terminal connected to said unetched section.

9. An electrode for electrolytic condensers comprising a strip of metal foil, a section of said strip of foil being etched, a section of said strip of foil being unetched, and an integral terminal tab for said electrode comprising the material of said unetched section.

10. A dry electrolytic condenser comprising a container, a pair of electrode foils therein, at least one of which is etched to increase its effective area, and film-formed, a film-maintaining electrolyte between said electrodes and a pair oi terminals connected to said electrodes, the etched electrode having a section much less fully etched than the remainder of the electrode surface, the terminal for said electrode being connected to said section. 4

11. An electrode for electrolytic condensers comprising a strip of metal 1011, a first section of said ioil being etched and a second section of said foil being much less etched than said first section, and a terminal connection for said electrode comprising the material of said second section and integral therewith.

12. An electrode for electrolytic condensers comprising a strip of metal foil, the major portion of which is etched and a small portion of which is much less etched than said major portion, and a terminal for said electrode compris ing the material of said less etched portion and integral with said electrode.

JOSEPH SENN WILLIAMS. 

